Electron discharge device and circuit



July 21, 1942. w s ws Y 2,290,819

ELECTRON DISCHARGE DEVICE AND CIRCUIT F'iledAugyg, 1940 3 Sheets-Sheefc l July 21, 1942. 1. WARSHAWSKY ELECTRON DISCHARGE DEVICE AND CIRCUIT Filed Aug. 9, 1940 3 Sheets-Sheet 2 livvenibr. WW

July 21, 1942.

l. WARSHAWSKY ELECTRON DISCHARGE DEVICE AND CIRCUIT Filed Aug. 9, 1940 s Sheets-Sheet s Patented July 21, 1942 UNITED STATE ELECTRON DISCHARGE DuvIcsANn I CIRCUIT Isador WarshawskmBrooklyn, N." Y." I h Application August 9, 1940, Serial No.'351,s22

14 Claims. (C

The present invention relates to electron discharge devices and more particularly to therm-' ionic vacuum tubes such as are employed in the radio art, and to circuit arrangements therefore.

The main object of this invention is to decrease the cathode heating time of thermionic vacuum tubes for normal electron emission, so that proper cathode heating is secured in a fraction of the time required at present.

Other objects and advantages of this invention will appear as the specification proceeds.

It is well known that when a radio receiver or similar electron discharge apparatus is switched on, an interval of time elapses before it begins to function, due to the time interval required for the cathodes ofthe thermionic vacuum tubes to attain the temperature necessary for normal electron emission.

Thermionic vacuum tubes have two types of cathodes, the directly heated cathode and the indirectly heated cathode. In the directly heated cathode type'of thermionic vacuum tube,

a filament heated by the fiow of electric current through it supplies the electrons. The filament may consist of tungsten, thoriated tungsten, or

of a metal coated with electron-emitting mate- In the case of radio receiving tubes, the time interval required for cathode heating to produce normal electron emission is generally quite short for the directly heated cathode type, but is considerably longer for the indirectly heated cathode type.

The present invention sets forth cathode heating arrangements for thermionic vacuum tubes which greatly reduce the cathode heating-time required to attain normal electron emission,so that radio receivers and similar electron discharge apparatus when switched on, begin to function in a fraction of the time required at present. In experiments performed, radio receivers using some of the cathode heating arrangements set forth' in this invention, and employing both indirectly and directly heated cathode type tubes of present day manufacture, attained full signal volume in two to four seconds after being switched on. These results may be improved upon, if the thermionic vacuum tubes employed are constructed to facilitate rapid cathode heating.

Decrease of the cathode heating time for. nor,- mal electron emission of the indirectly heated cathode type of thermionic vacuum tube is accomplished by the following two methods:

1. By applying a voltage greater than normal or rated voltage to the heater of the thermionic Vacuum tube until the cathode is brought to the proper temperature for normal electron emis-. sion, after which normal or rated voltage is applied to the heater. The application of greater than normal voltage to the heater of the thermionic vacuum tube results in greater than normal flow of current through the heater and therefore in rapid heating of the cathode.

2. By providing two separate heaters or a double-heater within the metallic cathode sleeve of the thermionic vacuum tube, one used for normal heating of the cathode, and the other I which produces more heat, is used for rapid heating of the cathode both heaters being switched on at the sametime, and when the cathode attains the proper temperature for normal electron emission, the heater which' causes rapid cathode heating. is switched off, and the cathode is thereafter heated only by the one causing normal heating,

Decrease of the cathode heating time for normal electron emission of the directly heated cathode type of thermionic vacuum tube is accomplished by the first method. In the case of radio receiving tubes, the directly heated cathode type heats up quite rapidly, so that it is necessary to apply rapid filament heating-only for the larger sizes of tubes.

In the application of the first method to effect rapid cathode heating, the greater than normal voltage applied to the filaments or heaters of thermionic vacuum tubes is generally from two to several times greater than normal or rated voltage, the directly heated cathode type requiring a lower value than the indirectly heated cathode type, for'tubes of equal rating.

The accompanying drawings forming a material part of this disclosure, together with the description serve to explain the principles of the invention.

Of the drawings:

Figures 1 to 6 are schematic diagrams of the heater and filament circuits of the thermionic vacuum tubes of radio receivers or other electron discharge apparatus, showing means for se- The elements or electrodes of the thermionic vacuum tubes not necessary for explanatory purposes have beenomitted to simplify the diagrams.

The various arrangements for securing rapid cathode heating of thermionic vacuum tubes employed in radio receivers and other electron discharge apparatus will now be described in detail, with the aid of the drawings.

In Fig. 1, the heating elements or filaments I of the directly heated cathode type thermionic vacuum tubes 2 are connected in series across the voltage supply circuit terminals 8 and-I through voltage-dropping resistors 8 and which are in parallel when main switch .8 is closed. This allows the application of greater than normal voltage to the filaments I of the thermionic vacuum tubes 2, resulting in rapid filament heating. When normal electron emission is attained by the filaments I, plate current flows through the coil 28 of relay l'l connected in the plate circuit of one of the thermionic vacuum tubes 2, in which the plate is denoted by H, thereby attracting armature 2i and thus open ing the circuit through resistor i'and also the filament circuit of a thermionic time-delay tube 28 which prevents a safety relay .28 connected in its plate circuit from operating. The plate of thethermionic time-delay tube 28 is denoted by l2. Only resistor 4 remains in thefilament circuit of the thermionic vacuum tubes 2 thereafter, allowing the application of normal voltage to the filaments I, resulting in normal heatin of the filaments.

The safety relay 28 which is'of the self-locking hand-reset type, automatically opens the.

circuit through resistor I, should relay I'l fail tion of its armature 2| also opens the filament circuit of the thermionic time-delay tube 28 somewhat before this tube attains substantially normal electron emission, thereby preventing safety relay 28 connected in its plate circuit from operating.

normal electron emission is attained by the thermionic vacuum tubes 2 subjected to rapid filament heating, because of some fault in the apparatus or relay, the thermionic time-delay tube 28 at the end of a predetermined time interval after the closing of main switch 8 attains substantially normal electron emission, and the resulting flow of plate current through the coil 21 of safety relay 28 causes the attraction of armature 24, thereby opening the circuit through resistor 8 and thus preventing damage to the thermionic vacuum tubes 2. When the failure of relay H to operate has been investigated and e the trouble remedied, safety relay 28 which has been locked in its open position is reset by hand.

In this circuit arrangement, the thermionic time-delay tube 28 draws filament current only.

for a very short time interval when main switch 8 is closed, until relay l1 operates and opens its filament circuit.

The circuit arrangement shown may be aloperating.

to operate when the thermionic vacuum tubes 2' attain normal electron emission, because of troubleeither in the apparatus or relay proper,

plied to the filament 28 of the thermionic timedelay tube 28 by means of a step-down transformer 88. The exact time of operation of the safety' relay 28 is accurately adjusted by the rheostat 8| in the filament circuit of the thermionic time-delay tube :0,- m-iby the variable re-.

sis'tor 88 shunted across the relay coil 21. I

The plate voltage for the thermionictime;

delay tube "is taken directly from the voltage.

The thermionic time-delay tube 28 i and the safety relay 28 connected in its plate circuit, to-:

gether constitute athermionic time-delay relay. j which opens the circuit through resistor 8 at the end of a predetermined time interval after, the

e The thermionic time-delay tube 28 is of a type that attains substantially normal electron emission in approximately the required time interval, and is of the directly heated cathode orfilament type, because this type of cathode can attain substantially normal electron emission in the shorttime interval required.

When relay i1 opens the circuit through resistor 8 on completion or rapid filament heating supply circuit so thatit is-independent of anyv rectifier or filter circuits, and is not affected by faults in these circuits which might cut oi! the plate voltage-and thus prevent safety relay 28 from operating'when necessary Safety relay 28 also prevents continuous rapid filament heating of the thermionic vacuum tubes 2, should armature 2l of relay l1 cease to be attracted during the operation of the radio receiver or "other electron discharge apparatus, due to some fault. When armature 2| ceases to be attracted, it closes the circuit through resistor 5 causing rapid filament heating of the thermionic vacuum tubes 2, but it also closes the filament or plate circuit (whichever is the case) of the thermionic time-delay tube 28, resulting in the flow of platev current through the coil 21 of safety relay 28, thereby attracting armature 24 and thus opening the circuit through resistor 5 and preventing damage to the thermionic vacuum tubes 2. When the trouble is remedied,

safety relay 28 is reset by hand.

The terminal 8| of relay coil 28 in relay I! may be supplied either with filtered D. C. voltage or with voltage taken directly from the voltage supply circuit. I

Fig. 2 diners from Fig. 1' only in that relay I1 is connected inthe plate circuit of a thermionic time-delay tube 28' instead of in the plate circuit of one of the thermionic vacuum tubes 2 closingof-main' switch 8, should relay l'l fail to operate, this time interval being somewhat longer than that required for the rapid filament heating of the thermionic vacuum tubes 2.

subjectedto rapid filament heating. The plate 0 this thermionic time-delay tube 28' is desnoted by l2, its filament by 29', and the rheostat in its filament circuit by 8|. The filament 28' of the thermionic time-delay tube 28' is supplied with voltage by the same transformer 8i! that supplies filament voltage to the thermionic time-delay tube 28, in the plate circuit of which safety relay 28 is connected.

The thermionic time-delay tube 28' together with relay l1 connected in its plate circuit constitute a thermionic time-delay relay which is adjusted to operate and break the circuit through resistor 8 when the thermionic vacuum tubes 2 attain normal electron emission upon being sub-.- jected to rapid filament heating. The exact time of operation of this thermionic time-delay relay of the thermionic vacuum tubes 2, the attrac- 7 is accurately adjusted bytherheostat 8| in the heated by a heating element or heater i.- Rapid 2 tion of greater than normal voltage to the bee.

ers l of the thermionic vacuum tubes}! until normal voltage to the heaters I to efiectfnormal filament circuit of the thermionic time-delay Similarly, in Figures 2, 4, and 6, wherein relay tube 28', or by the variable resistor 33 shunted I1 is shown connected in the plate circuit of a across the relay coil of relay H. thermionic time-delay tube 28, this tube may The terminal 34 of relay coil 20 in relay II perform a definite function in the radio receiver may be supplied either with filtered D. 0. volt- 6 or other electron discharge apparatus besides age or with voltage taken directly from the voltthat of operating the relay. A filament type age supply circuit.- power amplifier tube in a radio receiver, for in- The operation of circuit of Fig. 2 is otherwise 'stance,amay1function both as a power amplifier the same as that of Fig. 1. 1 f e and asja thermionic time-delaytube to operate Figures 3 and 4 are similar to Figureslfandil 10 the .relaydnits plate circuit. a In this case, the respectively, diifering only in that the therm f "plate vbltageffor thethermionic time-delay tube ionic vacuum tubes 2 are of the indirectly heated jmustbefi tered D. C- if the. ,thermionic timecathode type provided with a cathode 31Which-is -.is used only for the purpose of operelay in its plate circuit, its. plate volttaken directly from the voltage supcathode heating is accomplished by theapplica normal electron emission isattainedby theJcathQ A odes 3 whereupon relay l1 -operates 'iio: break e "28' (in Figures 1,2, 3, 4, 5, and the circuit. through resistor 5 therebyapplying a w v v andthe'relaygfl or .II in its plate circuit cathode heating of the thermionic vacuum tubes 'requires a certain value. of plate cur- 2 thereafter. Otherwise, the operation of the rn'trfor its" operation,.the time of operation of circuits of Figures 3and 4 is the same as that the thermionicftimeedelay relay '(which conof Figures 1 and 2 respectively. 5, sistsof the thermionictime-delaytube and the In Figures 1, 2, 3, and 4, although the fllarelayin its plate, circuit) may be controlled by ments or heaters l of the thermionic; vacuum means of-a variableresistor shunted across the tubes 2 are shown connected in series, they coil'of therelay to regulate the flow of plate curmay also be connected in parallel. rent throughthecoil.

Figures 5 and 6 are similar to Figures 3 and 4 The relay takes longest to operate when the respectively, differing only in some features. variable resistor'across its coil is adjusted so that The thermionic vacuum tubes 2 are of the inthe plate current flowing through the coil when directly heated cathode type, provided with two the thermionic timey tube 23 attains heating elements or heaters I and i within the normal electron emission is the minimum value metallic cathode sleeve 3, the heater 1 causing required for operation. If the variable resistor normal cathode heating, and the heater i which across the coil of the relay is adjusted so that produces more heat causing rapid cathode heatthe plate current flowing through the coil when ing. The heaters i used for normal cathode the thermionic time-delay tube attains normal heating are connected in parallel across the secelectron emission is greater than the minimum ondary 16 of a step-down transformer IS. The 40 value required for operation, the minimum value primary I8 of the transformer is connected of plate current flows sooner than before through across the voltage supply. circuit terminals 6 and the coil, causing operation of the relay, the great- I. The heaters I used for rapid cathode heat- 61' the plate current flowing through the coil ing are connected in series through the voltwhen the thermionic time-delay tube attains age-dropping resistor 35 across the voltage supnormal electron emission, the sooner the miniply circuit terminals 6 and 1. When main switch mum value of plate current required to operate 8 is closed, voltage is applied to both sets of the relay is reached.

heaters l and I, causing rapid heating of the In Figures 1, 2, 3, 4, 5, and 6, the variable recathodes 3 of the thermionic vacuum tubes 2. sistor 33 shunted across the coilof relay' I! or When normal electron emission is attained by safety relay 26 may therefore be'used to regulate the cathodes 3, relay i1 operates, opening the the flow of plate current through the coil and circuit of the set of heaters I used for rapid thereby to control the time of operation of the cathode heating, and also the plate circuit of relay, as mentioned Previously above;

the thermionic time-delay tube 28 to prevent Also, in Figures 1, 2, 3, 4, 5, and 6, condenser operation of safety relay 26. Thereafter the 25 shunted across the coil of safety relay 26,

,so that it in independent of faults in cathodes 3 of the thermionic vacuum tubes 2 are and condenser 25' shunted across the coil of relay normally heated by the set of heaters I. Otherl1, prevent chattering of the armature when wise, the features and operation of the circuits A. C. voltage is applied to the plate of the of Figures 5 and 6 are the same as those of thermionic time-delay tube 28 or 28' respec- Figures 3 and 4 respectively. tively, or to the plate of one of the thermionic In Figures 5 and 6, the sets of heaters I and vacuum tubes 2 subjected to rapid cathode heat- I' may each be connected in series or in parallel, ing when relay I1 is connected in its plate cirif desired. cuit.

In Figures 1, 3,. and 5, wherein relay I1 is In Figures 1 to 6 inclusive, the voltage at the shown connected in the plate circuit of one of 5 voltage supply circuit terminals 6 and I is A. (3., the thermionic vacuum tubes 2 subjected to rapid allowing the use of transformers and voltagecathode heating, this tube may perform a definite dropping resistors to provide the proper values function in a radio receiver or other electron disof filament or heater voltage for' the thermionic charge apparatus besides that of operating the vacuum tubes. The voltage at the voltage suprelay when plate current flows, or it may be ply circuit terminals 6 and 1 may also be D. C.,

used only for the purpose of operating the relay, voltage-dropping resistors being employed where in which case the plate voltage for the tube may necessary to provide the proper values of filabe taken directly from the voltage supply circuit, ment or heater voltage for the thermionic vacso that it is independent of faults in rectifier or uum tubes.

filter circuits. Although I have described my invention with a certain degree of particularity, it is understood that various changes or modifications may be made within the scope of the claims hereto attached without departing from the spirit of the invention.

What I claim is:

1. In electron discharge apparatus, the combination of thermionic vacuum tubes of the indirectly heated cathode type provided with two heaters within the metallic cathode sleeve, one set of heaters connected in series used-for rapid cathode heaLing-and the other set connected in parallel used for normal cathode heating, and means for applying voltage to both sets of heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying voltage thereafter only to the set of heaters of said thermionic vacuum tubes used for normal cathode heating.

2. In electron discharge apparatus, the combination of thermionic vacuum tubes of the indirectly heated cathode type provided with two heaters within the metallic cathode sleeve, one used for rapid cathode heating and the other for normal cathode heating, and means comprising a relay connected in the plate circuit of a thermionic time-delay tube for applying voltage to both heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying voltage thereafter only to the heater of said thermionic vacuum tubes used for normal cathode heating.

3. In electron discharge apparatus, the combination of thermionic vacuum tubes and relay means connected in the plate circuit of one of said thermionic vacuum tubes for applying greater than normal voltage to the heating elements of'said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heating elements of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal' electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

4. In electron discharge apparatus, the combination of thermionic vacuum tubes and means comprising a relay connected in the plate circuit lay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

5. In electron discharge apparatus, the combination of thermionic vacuum tubes of the indirectly heated cathode type and relay means connected in the plate circuit of one of said thermionic vacuum tubes for applying greater than normal voltage to the heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heaters of mal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

6. In electron discharge apparatus, the combination of thermionic vacuum tubes of the directly heated cathode type and relay, means connected in the plate circuit of one of said thermionic vacuum tubes for applying greater than normal voltage to the filaments of said thermionic vacuum tubes for rapid heating until normal electron emission is attained and for applying normal voltage to the filaments of said thermionic vacuum tubes thereafter for normal heating, and means comprising a thermionic time-delay relay which stops rapid filament heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

7. In electron discharge apparatus, th combination of thermionic vacuum tubes of th indirectly heated cathode type provided with two heaters within the metallic cathode sleeve, one,

used for rapid cathode heating and the other for normal cathodeheating, and relay means connected in the plate circuit of one of said thermionic vacuum tubes for applying voltage to both heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying voltage thereafter only to the heater of said thermionic vacuum tubes used for normal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

8. In electron discharge apparatus, the combination of thermionic vacuum tubes of the indirectly heated cathode type and means comprising a relay connected in the plate circuit of a thermionic time-delay tube for applying greater than normal voltage to the heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heater of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means failsto perform this function, to prevent damage to said thermthermionic vacuum tubes for rapid heating unsaid thermionic vacuum tubes thereafter for nor- 7 tained by said thermionic vacuumtubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

10. In electron discharge apparatus, the combination of thermionic vacuum tubes of the indirectly heated cathode type provided with two heaters within the metallic cathode sleeve, one used for rapid cathode heating and the other for normal cathode heating, and means comprising a relay connected in the plate circuit of a thermionic time-delay tube for applying voltage to both heaters of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying voltagee thereafter only to the heater of said thermionic vacuum tubes used for normal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes.

11. In electron discharge apparatus, the combination of thermionic vacuum tubes and relay means connected in.the plate circuit of one of said thermionic vacuum tubes for applying greater than normal voltage to th heating elements of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heating elements of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delay relay supplied with current directly from the voltage supply circuit which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, toprevent damage to said thermionic vacuum tubes.

12. In electron discharge apparatus, the combination of thermionic vacuum tubes and means comprising a relay connected in the plate circuit of a thermionic time-delay tube for applying greater than normal voltage to the heating elements of said thermionic vacuum tubes for'rapid cathode heating until normal electronemission is attained and for applying normal voltage to the heating elements of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delay relay which 'stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes, both said relay means supplied with current. directly from the voltage supply circuit.

13. In electron discharge apparatus, the combination of thermionic vacuum tubes and relay means connected in th plate circuit of one of said thermionic vacuum tubes for applying greater than normal voltage to the heating elements of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heating elements of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delayrelay which stops rapid cathode heating when normal electron emission is attained. by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes, and a variable resistor shunted acros the relay coil to adjust the time of operation of said latter relay means.

14. In electron discharge apparatus, the combination of thermionic vacuum tubes and means comprising a relay connected in the plate circuit of a thermionic time-delay tube for applying greater than normal voltage to the heating elements of said thermionic vacuum tubes for rapid cathode heating until normal electron emission is attained and for applying normal voltage to the heating elements of said thermionic vacuum tubes thereafter for normal cathode heating, and means comprising a thermionic time-delay relay which stops rapid cathode heating when normal electron emission is attained by said thermionic vacuum tubes if the first mentioned relay means fails to perform this function, to prevent damage to said thermionic vacuum tubes, and a variablemesistor shunted across each relay coil to adjust the time of operation of both said relay means.

ISADOR WARSHAWSKY. 

